Applications in Pharmaceutical Formulation or Technology
Xylitol is used as a noncariogenic sweetening agent in a variety of pharmaceutical dosage forms, including tablets, syrups, and coatings. It is also widely used as an alternative to sucrose in foods and as a base for medicated confectionery. Xylitol is finding increasing application in chewing gum,(1,2) mouthrinses,(3) and toothpastes(4) as an agent that decreases dental plaque and tooth decay (dental caries). Unlike sucrose, xylitol is not fermented into cariogenic acid end products(5) and it has been shown to reduce dental caries by inhibiting the growth of cariogenic Streptococcus mutans bacteria.(6,7) As xylitol has an equal sweetness intensity to sucrose, combined with a distinct cooling effect upon dissolution of the crystal, it is highly effective in enhancing the flavor of tablets and syrups and masking the unpleasant or bitter flavors associated with some pharmaceutical actives and excipients. In topical cosmetic and toiletry applications, xylitol is used primarily for its humectant and emollient properties, although it has also been reported to enhance product stability through a combination of potentiation of preservatives and its own bacteriostatic and bactericidal properties. Granulates of xylitol are used as diluents in tablet formulations,where they can provide chewable tablets with a desirable sweet taste and cooling sensation, without the ‘chalky’ texture experienced with some other tablet diluents. Xylitol solutions are employed in tablet-coating applications at concentrations in excess of 65% w/w Xylitol coatings are stable and provide a sweet-tasting and durable hard coating. In liquid preparations, xylitol is used as a sweetening agent and vehicle for sugar-free formulations. In syrups, it has a reduced tendency to ‘cap-lock’ by effectively preventing crystallization around the closures of bottles. Xylitol also has a lower water activity and a higher osmotic pressure than sucrose, therefore enhancing product stability and freshness. In addition, xylitol has also been demonstrated to exert certain specific bacteriostatic and bactericidal effects, particularly against common spoilage organisms.(8,9) Therapeutically, xylitol is additionally utilized as an energy source for intravenous infusion therapy following trauma.(10)
Xylitol occurs as a white, granular solid comprising crystalline,equidimensional particles having a mean diameter of about 0.4–0.6 mm. It is odorless, with a sweet taste that imparts a cooling sensation. Xylitol is also commercially available in powdered form,and several granular, directly compressible forms.(11) See also Section 17.
